"沒有為“FadeAnimation”類型定義方法“MultiTrackTween”"

Question

import 'package:flutter/material.dart';
import 'package:flutter/animation.dart';

class FadeAnimation extends StatelessWidget {
  final double delay;
  final Widget child;

  FadeAnimation(this.delay, this.child);

  ///build animation track
  @override
  Widget build(BuildContext context) {
    final tween = MultiTrackTween([
      Track("opacity")
          .add(Duration(milliseconds: 500), Tween(begin: 0.0, end: 1.0)),
      Track("translateY").add(
          Duration(milliseconds: 500), Tween(begin: -30.0, end: 0.0),
          curve: Curves.easeOut)
    ]);

    /// fade animation controller
    return ControlledAnimation(
      delay: Duration(milliseconds: (500 * delay).round()),
      duration: tween.duration,
      tween: tween,
      child: child,
      builderWithChild: (context, child, animation) => Opacity(
        opacity: animation["opacity"],
        child: Transform.translate(
            offset: Offset(0, animation["translateY"]), child: child),
      ),
    );
  }
}

Answer 1

MultiTrackTween MultiTrackTween 已重新設計為新的 MultiTween。 它具有相同的功能集，但更易於使用且完全類型安全。

查看 MultiTween README 了解更多詳情。>>> https://pub.dev/packages/sa_multi_tween

Answer 2

目前方法已經改變。 MultiTrackTween<\/code>更改為MultiTween<\/code> ， ControlledAnimation<\/code>更改為PlayAnimation<\/code>等等。 請看下面的例子：

// Create your Animation Example
enum AniProps { opacity, translateY }

class FadeAnimation extends StatelessWidget {
  final double delay;
  final Widget child;

  FadeAnimation(this.delay, this.child);

  @override
  Widget build(BuildContext context) {
    final tween = MultiTween<AniProps>()
        ..add(AniProps.opacity, Tween(begin: 0.0, end: 1.0))
        ..add(AniProps.translateY, Tween(begin: -30.0, end: 0.0), Duration(milliseconds: 500), Curves.easeOut);

    return PlayAnimation<MultiTweenValues<AniProps>>(
      delay: Duration(milliseconds: (500 * delay).round()),
      duration: tween.duration,
      tween: tween,
      child: child,
      builder: (context, child, animation) => Opacity(
        opacity: animation.get(AniProps.opacity),
        child: Transform.translate(
            offset: Offset(0, animation.get(AniProps.translateY)),
            child: child
        ),
      ),
    );
  }
}